The present invention relates to a bar stock feeder for a processing machine such as an automatic lathe and more particularly to a bar feeder for automatically feeding a bar into an axial hole formed in a spindle of an automatic lathe.
In an automatic lathe, especially in an automatic screw machine having a hollow spindle, a bar as a work is loaded from the rear end of the spindle and mounted in a collet. After machining operation, a machined portion of the bar is cut off by a cut-off tool to get a product. Subsequently, the cut-off tool is withdrawn and the bar is advanced a predetermined length necessary to the next machining. Accordingly, it is indispensable to provide an automatic lathe with a bar feeder for automatically feeding the bar.
A conventional bar feeder has a rod guide tube in which a push rod is slidably mounted for feeding a bar to a lathe. The bar is also rotated together with the spindle of the lathe. When the bar rotates at high speed, the bar vibrates in the rod guide tube and strikes the inner wall of the tube, causing the generation of loud noise. Further, damages, such as dent, scratch, crack and others, to the outer periphery of the bar are caused by the striking.
In order to solve these problems, the inner wall of the rod guide tube is lined with soft metal such as lead. However, lining work with lead for the inner wall is very difficult and expensive.